主题：【风云学会】大宗商品价格大跌是中国导致的吗？ -- 陈经

EROEI=Energy returned on energy invested

太阳能板的EROEI是多少？无数的人在算，总的来看不理想。

我随便google一篇做个参考：

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7. Conclusion and policy implications

The calculated value for ERoEI is dimensionless, constituting the energy return (2203 kW he/m2) divided by the energy invested (2664 kW he/m2) – a ratio of 0.82. It is estimated that these numbers could have an error of ±15%, so that, despite a string of optimistic choices resulting in low values of energy investments, the ERoEI is significantly below 1. In other words, an electrical supply system based on today’s PV technologies cannot be termed an energy source, but rather a non-sustainable energy sink or a non-sustainable NET ENERGY LOSS. The methodology recommended by the expert working group of the IEA appears to yield EROI levels which lie between 5 and 6, (see Section 4.1), but which are really not meaningful for determining the efficiency, sustainability and affordability of an energy source. The main conclusions to be drawn are:

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The result of rigorously calculating the “extended ERoEI” for regions of moderate insolation levels as experienced in Switzerland and Germany proves to be very revealing. It indicates that, at least at today's state of development, the PV technology cannot offer an energy source but a NET ENERGY LOSS, since its ERoEIEXT is not only very far from the minimum value of 5 for sustainability suggested by Murphy and Hall (2011), but is less than 1.

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Our advanced societies can only continue to develop if a surplus of energy is available, but it has become clear that photovoltaic energy at least will not help in any way to replace the fossil fuel. On the contrary we find ourselves suffering increased dependence on fossil energy. Even if we were to select, or be forced to live in a simpler, less rapidly expanding economic environment, photovoltaic technology would not be a wise choice for helping to deliver affordable, environmentally favourable and reliable electricity regions of low, or even moderate insolation, since it involves an extremely high expenditure of material, human and capital resources.

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Research and development should however, be continued in order in future to have more efficient conversion from sunlight to electricity and a cheaper, more reliable PV-technology offering increased efficiency and a longer, failure-free lifetime. The market will then develop naturally.